Research On Magnetic Field Monitoring Technology Based On Sensing Principles Of Various Optical Fiber

With the increasing demand for monitoring of magnetic field parameters in power system,biomedicine,Aeronautics and Astronautics,it is urgent to study new magnetic field monitoring technology with small size,high sensitivity,suitable for remote telemetry,and convenient for distributed network monitoring.Considering that fiber optic sensor has good flexibility,light weight,small weight,high accuracy and anti-electromagnetic interference,it is one of the main directions of sensor research in the future.So this paper presents the research of magnetic field monitoring technology based on various optical fiber sensing principles.The main work includes the following aspects:Firstly,according to the principle of fiber grating strain sensor and the characteristics of conductor Lorenz force,a fiber Bragg grating sensor is introduced to monitor the bending deformation of simply supported beam caused by Lorenz force,the deflection curve function of the simple supported beam caused by the measured magnetic field is derived,and the relationship between the central wavelength shift of FBG and the curvature of the simple supported beam is given.A two parameter monitoring system for the magnetic induction intensity and current of a simple supported beam based on the center wavelength shift of FBG is constructed,and the effective monitoring of the measured magnetic field intensity is realized.Secondly,according to the macro bending theory of single mode fiber and the characteristics of magnetic fluid liquid,an optical fiber magnetic field sensor based on the macro bending effect is developed.Then,we further connect FBG at the rear end of the macro bend optical fiber magnetic field sensor,and design a fiber optic magnetic field / temperature sensor based on macro bending effect,a double parameter measurement of the external magnetic field and temperature is realized.Thirdly,according to the self-imaging principle of no core fiber and characteristics of magnetic fluid liquid,it is carried out that magnetic field measurement theory model of no core fiber,numerical simulation and structure optimization design.The magnetic field sensor based on singlemode fiber-no core fiber structure(SN)and singlemode fiber-no core fiber-singlemode fiber(SNS)structure were made respectively,a method for identification of magnetic field intensity based on spectral feature analysis is proposed.Finally,The Sagnac interferometric optical fiber magnetic field sensor model based on the macro bending effect and SNS structure are studied respectively.A Sagnac interference magnetic field monitoring system based on the two structures is constructed,a method for identification of magnetic field intensity by Sagnac interference spectrum of characteristic analysis is proposed.